This PR includes changes to visualizations.sh, to include Linux support
There is also a small visual change, removing border around viz iframes
Coloring deps-viz nodes based on sharing-stats - white means very shared, black is little shared. The coloring is shifted to a pct-based point which I think seems more useful in practice - e.g. ocaml and lwt gets same white color.
The sharing-stats is based on direct-dependencies of all dependencies included in package